ASoC: imx-wm8962: Add a missing error check

My static checker complains that:

	sound/soc/fsl/imx-wm8962.c:196 imx_wm8962_probe() warn:
	we tested 'ret' before and it was 'false'

The intent was that we use "ret" to check imx_audmux_v2_configure_port().

Fixes: 8de2ae2a ('ASoC: fsl: add imx-wm8962 machine driver')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Otherwise, Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>